Facebook founder Mark Zuckerberg already gave $100 million to the Newark public school system earlier this year, and now the man who inspired "The Social Network" is gearing up to part with even more of his massive fortune. The 26-year-old billionaire is the latest tycoon promising to give away a majority of his wealth as a part of the "Giving Pledge," which was formed by Bill Gates and Warren Buffett.

The Wall Street Journal reports that Zuckerberg is among 15 other billionaires new to the pledge, including AOL co-founder Steve Case, investor Carl Icahn, former junk-bond king Michael Milken, Oracle Corp. founder Larry Ellison, film director George Lucas and New York Mayor Michael Bloomberg. Zuckerberg is worth about $6.9 billion.

The newspaper points out that many of those involved in the cause are already avidly involved in charity and notes that "it's unclear if the Giving Pledge has encouraged more giving." Regardless, Milken said, "I view this as a call to others who might in their thirties or forties use some of their creativity to get involved in philanthropy earlier in life."

Jesse Eisenberg, who played Zuckerberg in David Fincher's film about the young billionaire's rise, admits that while some of his actions appeared to be self-serving, he could see the good in the guy.

"I didn't think it was that difficult with this one, though, because he does things that are occasionally hurtful to other characters, but I think it's always coming from a real place. He prioritizes Facebook over his personal relationships," he said. "This is not something that I think is bad. His interest is elsewhere, so he severs these personal relationships he has in the movie in order to take Facebook in the direction that it needs to go. I think it's a completely defendable position."